Hierarchical Cu7S4-Cu9S8 heterostructure hollow cubes for photothermal aerobic oxidation of amines

Abstract Copper-based chalcogenides have been paid intensive attention as alternate photothermal catalysts for solar energy conversion. Despite considerable progress of copper sulfides nanostructure fabrication, combining independent copper sulfides polymorphs with various stoichiometries by forming heterojunction is still challenging. Herein, unique hierarchical nanosheet-assembled Cu7S4-Cu9S8 heterostructure hollow cubes with remarkable photothermal aerobic oxidation activity were prepared by a facile onepot chemical transformation route using Cu2O cubes as sacrificial template for the first time. In this reaction system, the introduction of proper sulfur source thioacetamide and moderate alkaline conditions plays a crucial role in phase transformation, and through tunning the reaction time, a series of Cu7S4, Cu7S4-Cu9S8, and Cu9S8 can be selectively prepared. Furthermore, the Cu7S4-Cu9S8 polymorphic heterostructure hollow cubes exhibit significantly enhanced photothermal aerobic oxidation performance of amines to the corresponding imines compared with the individual Cu7S4 and Cu9S8 in both N, N-dimethylformamide and acetonitrile solvent medium. Our results indicated that the strong near-infrared plasmonic absorption of Cu7S4-Cu9S8 facilitated hot carrier transport between Cu7S4 and Cu9S8, which subsequently promoted the catalytic reactions. Especially after uniform load of Au-Pt alloy nanoparticles, the photothermal aerobic oxidation activity was further enhanced due to their boosted synergistic local coupling enhancement effect between distinct components in the N, N-dimethylformamide solvent medium. Such enhanced photothermal reaction could effectively promote sunlight utilization in a wide range of photocatalytic reactions.